Question

What best defines the bilateral borders of a sarcomere

Answer 1

The bilateral borders of a sarcomere are defined by the Z-lines, also known as Z-discs. These structures mark the ends of a sarcomere and are composed of actin filaments that anchor the thin filaments in place. The Z-lines also serve as attachment points for the sarcomere to the rest of the muscle cell, providing structural stability and organization to the contractile unit.